An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A lack of → order. See → entropy.

→ dis-; → order.

Birâyegi, from birâyé, → disordered, + -(g)i noun suffix.

Lacking → order.

→ disorder + -ed.

Birâyé, from bi- "without," → a-, + râyé, → order.

A → differential equation containing only the first → derivative. For example, dy/dx = 3x and 2y(dy/dx) + 3x = 5.

→ first; → order; → differential; → equation.

A system of → formal logic that is an extension of → propositional logic. It is also known as → first-order predicate calculus and → predicate logic. FOL eliminates deficiencies of propositional logic by: representing → objects (their properties, relations and statements about them), introducing → variables, and introducing → quantifiers.

→ first; → order; → predicate; → logic.

For a → function with several → variables, the derivative, done only once, with respect to one of the variables. For example ∂u/∂x for u = u(x,y).

→ first; → order; → partial; → derivative.

Same as → first-order logic.

→ first; → order; → predicate; → calculus.

An optical spectrum, produced by a diffraction grating, in which the difference in path length of light from adjacent slits is one wavelength.

→ first; → order; → spectrum.

→ order of interference.

→ interference; → order.

1a) General: The way in which several items are arranged, as an indication of their relative importance or size or when each will be dealt with.
1b) Optics: → order of interference.
1c) Math.: The number of rows or columns of a → square matrix or → determinant.
1d) Math.: The highest → derivative appearing in a given → differential equation. For example,
d²y/dx² + 2y (dy/dx) - 3 = 0
is a differential equation of order two.
2) To arrange, regulate, or dispose things in their proper places. See also: → disorder, → first-order differential equation, → first-order partial derivative, → first-order spectrum, → interference order, → order of a tensor, → order of interference, → order of magnitude.

From O.Fr. ordre, from earlier ordene, from L. ordinem (nominative ordo) "row, rank, arrangement."

Râyé, noun related to râyânidan "to regulate, set in order," from Mid.Pers. râyânīdan "to arrange, organize," from rây- (Mod.Pers. ârây-, ârâyeš, ârâyidan "to arrange, adorn"), ârây-, ârâstan "to arrange, adorn;" O.Pers. rād- "to prepare," rās- "to be right, straight, true," rāsta- "straight, true" (Mod.Pers. râst "straight, true"); Av. rāz- "to direct, put in line, set," razan- "order;" Gk. oregein "to stretch out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Skt. rji- "to make straight or right, arrange, decorate;" PIE base *reg- "move in a straight line;" see also → direct.

The → number of → vertices.

→ order; → graph.

The maximum number of the indices (→ index) of a tensor.

→ order; → tensor.

A whole number which characterizes a particular position of an interference fringe according to whether there is interference arising from one, two, three, etc. wavelength difference of path. Same as → interference order

→ order; → interference.

Value of a number or of a physical quantity given roughly, usually expressed as a power of 10. Thus, 2.5 x 10⁵ and 6.4 x 10⁵ are of the same order of magnitude, and 2 x 10⁷ is 2 orders of magnitude greater than either.

→ order; → magnitude.

Characterized by → order; arranged according to a rule. → ordered tree.

→ order + -ed.

In → graph theory, a → tree in which the → children of each → vertex are ordered.

→ ordered; → tree.

An n extension of → first-order logic that quantifies not only → variables that range over → individuals, but also quantifies over → relations.

→ second; → order; → predicate; → logic.

A set in which every → nonempty → subset has a minimum element.

→ well; → order; → set.